Apparatus for etching high aspect ratio features

ABSTRACT

Embodiments of the invention provide a method and apparatus, such as a processing chamber, suitable for etching high aspect ratio features. Other embodiments include a showerhead assembly for use in the processing chamber. In one embodiment, a processing chamber includes a chamber body having a showerhead assembly and substrate support disposed therein. The showerhead assembly includes at least two fluidly isolated plenums, a region transmissive to an optical metrology signal, and a plurality of gas passages formed through the showerhead assembly fluidly coupling the plenums to the interior volume of the chamber body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. No. 11/381,523, filed May 3, 2006 (APPM/10536), whichis incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to a vacuum processingchamber for etching high aspect ratio feature in semiconductorsubstrates and the like.

2. Description of the Related Art

The demand for faster, more powerful integrated circuits (IC) deviceshas introduced new challenges for IC fabrication technology, includingthe need to etch high aspect ratio of features such as trenches or viason a substrate such as a semiconductor wafer. For example, deep trenchstorage structures used in some dynamic random access memoryapplications require deep high aspect ratio trenches etched into asemiconductor substrate. Deep silicone trench etching is typicallycarried out in a reactive ion etching (RIE) process utilizing siliconoxide mask.

One conventional system which has shown robust performance in etchinghigh aspect ratio features is the CENTURA HART™ Etch System, availablefrom Applied Materials, inc. located in Santa Clara, Calif. The HART™etching system utilizes a MERIE reactor capable of etching trencheshaving aspect ratios up to 70:1 while maintaining trench depthuniformity of 5 percent from center to edge. However, in order to enablefabrication of integrated circuits having sub-90 nm critical dimensions,circuit designers have demanded improved uniformity trench uniformity atevent high aspect ratios. Thus, it would be desirable to improve etchingperformance to enable the realization of next generation devices.

Therefore, there is a need for an improved apparatus for etching highaspect ratio features.

SUMMARY OF THE INVENTION

Embodiments of the invention provide a method and apparatus, such as aprocessing chamber, suitable for etching high aspect ratio features.Other embodiments include a showerhead assembly for use in theprocessing chamber.

In one embodiment, a processing chamber includes a chamber body having ashowerhead assembly and substrate support assembly disposed therein. Theshowerhead assembly includes at least two fluidly isolated plenums, aregion transmissive to an optical metrology signal, and a plurality ofgas passages formed through the showerhead assembly fluidly coupling theplenums to the interior volume of the chamber body.

In another embodiment, a processing chamber includes a chamber bodyhaving a showerhead assembly and substrate support assembly disposedtherein. The showerhead assembly includes an inner gas flow zone, anouter gas flow zone, and a region transmissive to an optical metrologysignal. The inner and outer zones are fluidly isolated from each other.The substrate support assembly includes at least two independentlycontrollable and laterally spaced temperature zones. An opticalmetrology system is arranged to view an interior volume of the chamberbody through the transmissive region of the showerhead assembly. Thesubstrate support assembly has a bias power source and at least twoplasma power sources coupled thereto.

In another embodiment, a processing chamber includes a chamber bodyhaving a gas distribution plate and substrate support assembly disposedtherein. The gas distribution plate has an outer set of gas flow holes,an inner set of gas flow holes, and a set of optical metrology holes. Aninner gas flow zone is fluidly coupled to an interior volume of thechamber body through the first set of gas flow holes. An outer gas flowzone is fluidly isolated from the inner zone and coupled to the interiorvolume through the second set of gas flow holes. A ceramic plug having aplurality of holes is aligned with the optical metrology holes and awindow. The substrate support assembly is disposed in the chamber bodyand has at least two independently controllable laterally spacedtemperature zones. An optical metrology system is arranged to view theinterior volume of the chamber body through an optical passage definedby the window, the holes in the plug and optical metrology holes. Thesubstrate support assembly has a bias power source and at least twoplasma power sources coupled thereto.

In another embodiment, a method for etching high aspect ratio featuresis provided that includes providing a plurality of gases to a mixingmanifold, controlling a ratio of mixed gases flowing from the mixingmanifold to different regions of a processing chamber; and providing atleast one direct injection gas to at least one of the regions of theprocessing chamber bypassing the mixing manifold.

In yet another embodiment, a showerhead assembly is provided thatincludes a gas distribution plate coupled to an upper section. The gasdistribution plate has an outer set of gas flow holes, and inner set ofgas flow holes, and a set of optical metrology holes. The upper sectionhas a first plenum fluidly coupled to the outer set of gas flow holesand a second plenum fluidly coupled to the inner set of gas flow holes.The plenums are fluidly isolated within the upper section. A ceramicplug is disposed through the upper section and has an opticallytransmissive region aligned with the optical metrology holes.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a sectional view of one embodiment of a processing chamber ofthe present invention;

FIG. 2 is a sectional view of one embodiment of a showerhead;

FIG. 3 is a perspective view of one embodiment of a plug of theshowerhead of FIG. 2

FIG. 4 is a sectional view of the showerhead of FIG. 2;

FIG. 5 is another sectional view of the showerhead of FIG. 2;

FIG. 6 is a partial sectional view of the showerhead taken along sectionlines 6-6 of FIG. 5;

FIG. 7 is a sectional view of another embodiment of a showerhead;

FIG. 8 is one embodiment of a gas control a schematic diagramillustrating the routing and control of gases for the processing chamberof FIG. 1;

FIGS. 9-10 are perspective and partial sectional views of one embodimentof a liner; and

FIG. 11 is a partial sectional view of a substrate support assemblysupporting one embodiment of a cover ring.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures. It is contemplated that elements of one embodiment maybe advantageously utilized in other embodiments without furtherrecitation.

DETAILED DESCRIPTION

FIG. 1 is a sectional view of one embodiment of a processing chamber 100suitable for etching high aspect ratio features in a substrate 144.Although the processing chamber 100 is shown including a plurality offeatures that enable superior etching performance, it is contemplatedthat other processing chambers may be adapted to benefit from one ormore of the inventive features disclosed herein.

The processing chamber 100 includes a chamber body 102 and a lid 104which enclose an interior volume 106. The chamber body 102 is typicallyfabricated from aluminum, stainless steel or other suitable material.The chamber body 102 generally includes sidewalls 108 and a bottom 110.A substrate access port (not shown) is generally defined in a side wall108 and a selectively sealed by a slit valve to facilitate entry andegress of the substrate 144 from the processing chamber 100. An exhaustport 126 is defined in the chamber body 102 and couples the interiorvolume 106 to a pump system 128. The pump system 128 generally includesone or more pumps and throttle valves utilized to evacuate and regulatethe pressure of the interior volume 106 of the processing chamber 100.In one embodiment, the pump system 128 maintains the pressure inside theinterior volume 106 at operating pressures typically between about 10mTorr to about 20 Torr.

The lid 104 is sealingly supported on the sidewall 108 of the chamberbody 102. The lid 104 may be opened to allow excess to the interiorvolume 106 of the processing chamber 100. The lid 104 includes a window142 that facilitates optical process monitoring. In one embodiment, thewindow 142 is comprised of quartz or other suitable material that istransmissive to a signal utilized by an optical monitoring system 140.

The optical monitoring system 140 is positioned to view at least one ofthe interior volume 106 of the chamber body 102 and/or the substrate 144positioned on a substrate support assembly 148 through the window 142.In one embodiment, the optical monitoring system 140 is coupled to thelid 104 and facilitates an integrated etch process that uses opticalmetrology to provide information that enables process adjustment tocompensate for incoming pattern inconsistencies (such as CD, thickness,and the like), provide process state monitoring (such as plasmamonitoring, temperature monitoring, and the like), and/or end pointdetection, among others. One optical monitoring system that may beadapted to benefit from the invention is the EyeD® full-spectrum,interferometric metrology module, available from Applied Materials,Inc., of Santa Clara, Calif.

In one embodiment, the optical monitoring system 140 is capable ofmeasuring CDs, film thickness and plasma attributes. The opticalmonitoring system 140 may use one of more non-destructive opticalmeasuring techniques, such as spectroscopy, interferometry,scatterometry, reflectometry, and the like. The optical monitoringsystem 140 may be, for example, configured to perform an interferometricmonitoring technique (e.g., counting interference fringes in the timedomain, measuring position of the fringes in the frequency domain, andthe like) to measure the etch depth profile of the structure beingformed on the substrate 144 in real time. Details of how to use examplesof an optical monitoring have been disclosed in commonly assigned U.S.Application Ser. No. 60/479,601, titled “Method and System forMonitoring an Etch Process”, filed on Jun. 18, 2003, U.S. Pat. No.6,413,837, titled “Film Thickness Control Using SpectralInterferometry”, issued on Jul. 2, 2002, and U.S. Application Ser. No.60/462,493, titled “Process Control Enhancement and Fault DetectionUsing In-Situ and Ex-situ Metrologies and Data Retrieval In MultiplePass Wafer Processing”, filed on Apr. 11, 2003, all of which areincorporated by reference in their entireties.

A gas panel 158 is coupled to the processing chamber 100 to provideprocess and/or cleaning gases to the interior volume 106. In theembodiment depicted in FIG. 1, inlet ports 132′, 132″ are provided inthe lid 104 to allow gases to be delivered from the gas panel 158 to theinterior volume 106 of the processing chamber 100.

A showerhead assembly 130 is coupled to an interior surface 114 of thelid 104. The showerhead assembly 130 includes a plurality of aperturesthat allow the gases flowing through the showerhead assembly 130 fromthe inlet port 132 into the interior volume 106 of the processingchamber 100 in a predefined distribution across the surface of thesubstrate 144 being processed in the chamber 100.

The showerhead assembly 130 additionally includes a region transmissiveto an optical metrology signal. The optically transmissive region orpassage 138 is suitable for allowing the optical monitoring system 140to view the interior volume 106 and/or substrate 144 positioned on thesubstrate support assembly 148. The passage 138 may be a material, anaperture or plurality of apertures formed or disposed in the showerheadassembly 130 that is substantially transmissive to the wavelengths ofenergy generated by, and reflected back to, the optical measuring system140. In one embodiment, the passage 138 includes a window 142 to preventgas leakage that the passage 138. The window 142 may be a sapphireplate, quartz plate or other suitable material. The window 142 mayalternatively be disposed in the lid 104.

In one embodiment, the showerhead assembly 130 is configured with aplurality of zones that allow for separate control of gas flowing intothe interior volume 106 of the processing chamber 100. In the embodimentFIG. 1, the showerhead assembly 130 as an inner zone 134 and an outerzone 136 that are separately coupled to the gas panel 158 throughseparate inlets 132.

FIG. 2 is a sectional view of one embodiment of the showerhead assembly130. The showerhead assembly 130 generally includes a base 202, upperand lower plenum plates 204, 206, a plug 208 and a gas distributionplate 210. The upper and lower plenum plates 204, 206 are coupled toeach other in a spaced-apart relation and disposed in a recess 270formed in the base 202 to define the upper structure of the showerheadassembly 130. The plenum region defined between the plates 204, 206 isfluidly separated into at least two zones by a barrier wall 236. In theembodiment depicted in FIG. 2, the wall 236 separates an inner plenum218 from an outer plenum 220. The plenums 218, 220 are respectively fedby the inlet ports 132′, 132″ formed in the base 202 by gas feeds 222,224 defined through the base 202 and upper plenum plate 204. Gaspassages 242, discussed in detail below, are defined through the lowerplenum plate 204 and gas distribution plate 210 allow gases in theplenums 218, 220 to enter the interior volume 106 of the chamber 100.The number and distribution of the passages 242 are selected to providea predefined distribution of gases into the chamber 100.

The recess 270 formed in the base 202 may include one or more steps forlocating the plates 204, 206. In the embodiment depicted in FIG. 2, therecess 270 includes an inner step 240 and an outer step 284. The innerstep 240 provides a surface against which the lower plenum plate 206 isdisposed. A seal, un-numbered, is provided between the inner step 240and the lower plenum plate 206 to prevent gas leakage. The outer step284 provides a recess into the base 202 which allows the gasdistribution plate 210 to cover the gap defined between the lower plenumplate 206 and base 202.

The base 202 generally includes a lip 216 extending outward from aninner outer diameter 286. A ledge 288, defined between the lip 216 andthe inner outer diameter 286, supports the showerhead assembly 130 onthe lid 104 and/or outer liner 116. The ledge 288 is generallyperpendicular to the lip 216 and the inner outer diameter 286, which aregenerally parallel and concentric to a centerline of the chamber body.

The inner outer diameter 286 ends at a bottom surface 290 of the base202. The bottom surface 290 generally faces the processing area, and assuch, may be coated with a protective material, such as Y₂O₃.

The base 202 also includes a plurality of channels 212 formed thereinthat are coupled to a fluid source 214. The fluid source 214 provides aheat transfer fluid, such as air or water, which is circulated throughthe channels 212 to regulate the temperature of the base 202 andshowerhead assembly 130.

The passage 138 is formed through the showerhead assembly 130 tofacilitate monitoring of chamber processes and/or substrate attributesby the optical monitoring system 140. The passage 138 includes coaxiallyaligned apertures 226, 264, 254, 262. The first aperture 226 is formedin the base 202. The second aperture 264 is formed in the upper plenumplate 204. The third aperture 254 is formed in the lower plenum plate206, while the aperture 262 is formed in the gas distribution plate 210.The window 142 is sealingly disposed in the passage 138 to prevent gasleakage through the showerhead assembly 130 to the optical monitoringsystem 140. In the embodiment depicted in FIG. 2, a recess 258 isprovided in the upper plenum plate 204 to house the window 142. O-rings,not labeled with reference numerals in FIG. 2, are provided to seal thewindow 142 to the upper plenum plate 204 and the base 202.

The plug 208 is disposed at least in the second aperture 264 formed inthe upper plenum plate 204. The plug 208 is configured to betransmissive to the signal utilized by the optical monitoring system140. In one embodiment, the plug 208 includes a plurality of high aspectratio passages 260 which allow the optical monitoring system 140 tointerface with the interior volume of the chamber 100 while preventingplasma formation within the passages 260. In one embodiment, thepassages 260 have an aspect ratio (height to diameter) of at least about10:1, for example 14:1. In another embodiment, passages 260 have adiameter of less than or comparable to the DEBYE length and/or theelectron mean free path, for example less than about 1.5 mm, forexample, about 0.9 mm. In another embodiment, passages 260 define anopen area of up to about 60 percent open area. In yet anotherembodiment, about 37 of passages 260 are formed through the plug 208.

The passages 260 formed in the plug 208 are aligned with metrologyapertures 262 formed in the gas distribution plate 210. The metrologyapertures 262 are clustered at the center of the gas distribution plate210, and have a density, diameter (or width), profile, and open areasuitable for facilitating the effective transmission of the metrologysignal through the gas distribution plate 210. In one embodiment, thenumber and sectional profile of the apertures 262 are similar to that ofthe passages 260. The window 142 makes the passages 260, 262 blind in agas flow sense, while allowing optical transmission. Thus, the passages260, 262 and window 142 facilitate optical monitoring by the opticalmonitoring system 140 within the chamber 100 without vacuum loss orplasma damage to the structure defining the optical view path.

A tapered seat 256 is formed in the upper plenum plate 204 coupling thesecond aperture 264 to the recess 258. The tapered seat 256 isconfigured to mate with a flared section 304 of the plug 208, as shownin FIG. 3. The flared section 304 is positioned between a head 302 andelongated stem 306 of the plug 208.

The plug 208 is generally fabricated from a material compatible withprocess chemistries. In one embodiment, the plug 208 is fabricated froma dielectric material, such as a ceramic. In another embodiment, theplug 208 is aluminum.

The upper and lower plenum plates 204, 206 are coupled to the base 202.The upper plenum plate 204 is also coupled to the lower plenum plate206. In one embodiment, upper plenum plate 204 is coupled to the lowerplenum plate 206 by a plurality of pins 228. The ends of the pins 228are inserted into holes 230, 232 respectively formed in the upper andlower plenum plates 204, 206. The pins 228 may be secured by a lockingcompound or adhesive, or may be pressed for friction fit. The sectionalview of FIG. 4 illustrates the pins 228 extending from holes 232 formedin the lower plenum plate 206. As the holes 230, 232 do not extendthrough the respective plates 204, 206, gas leakage around the pins 228is prevented.

Referring additionally to the sectional views of FIGS. 5-6, the gasdistribution plate 210 is coupled to at least one of the lower plenumplate 206 or base 202. In one embodiment, an adhesive layer 502 couplesthe gas distribution plate 210 to the lower plenum plate 206 in a mannerthat defines a plurality of annular plenums 508 therebetween. Theplenums 508 allow passages 242 positioned along common radii or range ofradius to be fluidly coupled to enhance flow uniformity of gases passingthrough the showerhead assembly 130 at a predefined radial position.

In one embodiment, the adhesive layer 502 includes a plurality ofadhesive rings 504 and a plurality of adhesive beads 506. The pluralityof adhesive rings 504 are arranged concentrically to bound the plenums508. The plurality of adhesive beads 506 are also arrangedconcentrically between the rings 504. The beads 506 are spaced from therings 504 to allow gases to flow around the beads 506 between passages242 sharing a common plenum 508.

Returning to FIG. 2, the portion of the passages 242 formed in the lowerplenum plate 206 generally includes a first bore hole 244, an orificehole 246 and a second bore hole 248. The first bore hole 244 is open tothe plenum 220 (or 218) to allow gases to enter the passage 242. Thesecond bore hole 248 is aligned with the hole 250 formed through the gasdistribution plate 210 for delivering gas into the interior volume 106of the chamber 100.

In one embodiment, the bore holes 244, 248 are substantially greater inboth diameter and depth relative to the orifice hole 246 to facilitateefficient fabrication of the passage 242. In the embodiment depicted inFIG. 2, the first bore hole 244 is open to the plenum 220 (or 218) has agreater diameter and lower aspect ratio than the second bore hole 248which is open to the interior volume 106 of the chamber 100.

The gas distribution plate 210 may be a flat disc. The holes 250 arespatially distributed in a pattern outward of the center region of thegas distribution plate 210. One set of holes 250 are fluidly coupled tothe outer plenum 136, while a second set of holes 250 are fluidlycoupled to the inner plenum 134. The holes 250, as being part of thepassages 242, allow gas passage through the gas distribution plate 210and into the interior volume 106 of the chamber 100.

To extend the service life of the showerhead assembly 130, the gasdistribution plate 210 is at least one of fabricated or coated withYttrium or an oxide thereof. In one embodiment, the gas distributionplate 210 is fabricated from bulk Yttrium or oxide thereof to provideresistance to fluorinated chemistries. In other embodiment, the gasdistribution plate 210 is fabricated from bulk Y₂O₃.

FIG. 7 is another embodiment of a showerhead assembly 700. Theshowerhead assembly 700 is substantially similar to the showerheadassembly 138, having a plug 708 for preventing plasma light-up in apassage 726 formed through the showerhead assembly 700 to facilitateoptical metrology. A window 142 is provided in the passage 726 as a gasbarrier.

The showerhead assembly 700 includes a base plate 702 coupled to aplenum plate 704. The plenum plate 704 has a pair of annular grooves712, 714 formed therein that are bounded by the base plate 702 fordefining inner and outer plenums 716, 718. Gases are provided to theplenums 716, 718 through respective ports 132′, 132″ from the gas panel158, thereby allowing the gases to be individually controlled in eachzone 134, 136 extending into the interior volume 106 of the chamber 100from the showerhead assembly 700.

The plenum plate 704 includes a plug hole 720 for receiving the plug708. The plug hole 720 aligns with an aperture 706 formed in the base702 and metrology holes 728 formed in the gas distribution plate 710 todefine the passage 726. The plug hole 720 generally includes a recess722 for receiving the window 142 and a tapered seat 724. The taperedseat 724 engages the flared region of the plug 708 to locate the plug708 within the plenum plate 704.

FIG. 8 is one embodiment of a schematic diagram illustrating the routingand control of gases delivered from the gas panel 158 to the processingchamber 100. The gas panel 158 generally includes a plurality of gassources coupled to a mixing manifold 810 and a flow controller 814.

Generally, flow from each of the gas sources is controlled by a controlvalve 808. The control valve 808 controls at least one of the flow,rate, pressure, and the like of the fluids provided from the sources.The control valve 808 may include more than one valve, regulator and/orother flow control device.

In the one embodiment, the gas panel 158 includes at least one directgas source 802, at least one processing gas source 804 and at least onecarrier gas source 806. The processing gas sources 804 and the carriergas source 806 are fluidly coupled to the mixing manifold 810 byindividual gas lines. The various gases from the sources 804, 806 arecombined in the mixing manifold 810 into pre-delivery gas mixture. Assuch, the composition of the pre-delivery gas mixture in the mixingmanifold 810 may be chosen by selectively opening the respective valves808 so that a predetermined combination of carrier and process gases806, 804 are combined. For example, at least one processing gas from theprocessing gas source 804, and optionally at least one carrier gas fromthe carrier gas source 806 may be combined in the mixing manifold 810 inany combination. Examples of processing gases include SiCl₄, HBr, NF₃,O₂ and SiF₄, among others. Examples of carrier gases include N₂, He, Ar,other gases inert to the process and non-reactive gases.

The flow controller 814 is coupled to the mixing manifold 810 by aprimary gas feed 812. The flow controller 814 is configured to split thepre-delivery gas mixture flowing from the mixing manifold 810 intosub-mixtures delivered to the chamber 100 through separate gas feedlines. Generally, the number of gas feed lines is commensurate with thenumber of zones (or isolated plenums) defined in the showerhead assembly130. In the embodiment depicted in FIG. 8, two gas feed lines 816, 818couple the flow controller 814 to the respective inlet ports 132′, 132″.

The flow controller 814 is generally configured to control the ratio ofsub-mixtures flowing in each feed line 816, 818. In this manner, theratio of gas sub-mixtures flowing to each zone, and ultimately to eachregion of the substrate 144, may be controlled. The flow controller 814may split the pre-delivery gas mixture using electronic or mechanicaldevices. In one embodiment, the flow controller 814 is able todynamically control the ratio in response to a signal from thecontroller 150, thereby enabling the ratio to be changed between batchesof substrates, between substrates, and/or in-situ processing a singlesubstrate. In another embodiment, the flow controller 814 is set suchthat the ratio is fixed between the lines 816, 818. The ratio may be setby one or more orifices disposed in the flow controller 814 such thatthe flow from the primary gas feed 812 is preferentially split betweenthe gas feed lines 816, 818.

In one embodiment, the flow controller 814 provides more gas to theinner zone 134 than the outer zone 136. In still another embodiment, theflow controller 814 provides more gas to the outer zone 136 than theinner zone 134. In still another embodiment, the flow controller 814provides more gas to the inner zone 134 than the outer zone 136 for afirst period of substrate processing, then changes the ratio in-situprocessing the substrate to provide more gas to the outer zone 136 thanthe inner zone 134 for a second period of substrate processing. It iscontemplated that the flow controller 814 may be configured to controlthe ratio between flows delivered to different zones in the processchamber 100 in other sequences or ratios.

A directly injected gas is also provided to the interior volume 106 ofthe processing chamber 100 from the direct injection gas source 802 ofthe gas panel 158. The amount of directly injected gas flowing from thedirect injection gas source 802 is controlled by a valve 808.

In one embodiment, the directly injected gas is provided to at least oneof the gas feeds 816, 818. In another embodiment, the directly injectedgas is teed into two direct feed lines 820, 822 that are respectivelyteed into the gas feed lines 816, 818. In yet another embodiment, thedirectly injected gas is provided to at least one of the gas feedscoupled to the inlet ports 132′, 132″. In still another embodiment, thedirectly injected gas is provided to at least one of the plenums 218,220 (716, 718) of the showerhead assembly 130 (700).

In the embodiment depicted in FIG. 8, the same amount of directlyinjected gas is provided to each zone 134, 136. Optionally, a secondflow controller 824 (shown in phantom, and similar to the flowcontroller 814) may be utilized to provide different ratios of directlyinjected gas to each of the zones 134, 136.

Returning to FIG. 1, a substrate support assembly 148 is disposed in theinterior volume 106 of the processing chamber 100 below the showerheadassembly 130. The substrate support assembly 148 holds the substrate 144during processing. The substrate support assembly 148 generally includesa plurality of lift pins (not shown) disposed therethrough that areconfigured to lift the substrate from the support assembly 148 andfacilitate exchange of the substrate 144 with a robot (not shown) in aconventional manner.

In one embodiment, the substrate support assembly 148 includes amounting plate 162, a base 164 and an electrostatic chuck 166. Themounting plate 162 is coupled to the bottom 110 of the chamber body 102includes passages for routing utilities, such as fluids, power lines andsensor leads, among other, to the base 164 and chuck 166.

At least one of the base 164 or chuck 166 may include at least oneoptional embedded heater 176, at least one optional embedded isolator174 and a plurality of conduits to control the lateral temperatureprofile of the support assembly 148. In the embodiment depicted in FIG.1, one annular isolator 174 and two conduits 168, 170 are disposed inthe base 164, while a resistive heater 176 is disposed in the chuck 166.The conduits are fluidly coupled to a fluid source 172 that circulates atemperature regulating fluid therethrough. The heater 176 is regulatedby a power source 178. The conduits 168, 170 and heater 176 are utilizedto control the temperature of the base 164, thereby heating and/orcooling the electrostatic chuck 166, thereby controlling, at least inpart, the temperature of the substrate 144 disposed on the electrostaticchuck 166.

The two separate cooling passages 168, 170 formed in the base 164 defineat least two independently controllable temperature zones. It iscontemplated that additional cooling passages and/or the layout of thepassages may be arranged to define additional temperature control zones.In one embodiment, the first cooling passage 168 is arranged radiallyinward of the second cooling passage 170 such that the temperaturecontrol zones are concentric. It is contemplated that the passages 168,170 may radially orientated, or have other geometric configurations. Thecooling passages 168, 170 may be coupled to a single source 172 of atemperature controlled heat transfer fluid, or may be respectivelycoupled to a separate heat transfer fluid source.

The isolator 174 is formed from a material having a differentcoefficient of thermal conductivity than the material of the adjacentregions of the base 164. In one embodiment, the isolator 174 has asmaller coefficient of thermal conductivity than the base 164. In afurther embodiment, the isolator 174 may be formed from a materialhaving an anisotropic (i.e. direction-dependent) coefficient of thermalconductivity. The isolator 174 functions to locally change the rate ofheat transfer between the support assembly 148 through the base 164 tothe conduits 168, 170 relative to the rate of heat transfer thoughneighboring portions of the base 164 not having an isolator in the heattransfer path. An isolator 174 is laterally disposed between the firstand second cooling passages 168, 170 to provide enhanced thermalisolation between the temperature control zones defined through thesubstrate support assembly 148.

In the embodiment depicted in FIG. 1, the isolator 174 is disposedbetween the conduits 168, 170, thereby hindering lateral heat transferand promoting lateral temperature control zones across the substratesupport assembly 148. Thus, by controlling the number, shape, size,position and coefficient of heat transfer of the inserts, thetemperature profile of the electrostatic chuck 166, and the substrate144 seated thereon, may be controlled. Although the isolator 174 isdepicted in FIG. 1 shaped as an annular ring, the shape of the isolator174 may take any number of forms.

An optional thermally conductive paste or adhesive (not shown) may bedisposed on between the base 164 and the electrostatic chuck 166. Theconductive paste facilitates heat exchange between the electrostaticchuck 166 and the base 164. In one exemplary embodiment, the adhesivemechanically bonds the electrostatic chuck 166 to base 164.Alternatively (not shown), the substrate support assembly 148 mayinclude a hardware (e.g., clamps, screws, and the like) adapted forfastening the electrostatic chuck 166 to the base 164.

The temperature of the electrostatic chuck 166 and the base 164 ismonitored using a plurality of sensors. In the embodiment depicted inFIG. 1, a first temperature sensor 190 and a second temperature sensor192 are shown in a radially spaced orientation such that the firsttemperature sensor 190 may provide the controller 150 with a metricindicative of the temperature of a center region of the support assembly148 while the second temperature sensor 192 provide the controller 150with a metric indicative of the temperature of a perimeter region of thesupport assembly 148.

The electrostatic chuck 166 is disposed on the base 164 and iscircumscribed by a cover ring 146. The electrostatic chuck 166 may befabricated from aluminum, ceramic or other materials suitable forsupporting the substrate 144 during processing. In one embodiment, theelectrostatic chuck 166 is ceramic. Alternatively, the electrostaticchuck 166 may be replaced by a vacuum chuck, mechanical chuck, or othersuitable substrate support.

The electrostatic chuck 166 is generally formed from ceramic or similardielectric material and comprises at least one clamping electrode 180controlled using a chucking power source 182. The electrode 180 (orother electrode disposed in the chuck 166 or base 164) may further becoupled to one or more RF power sources for maintaining a plasma formedform process and/or other gases within the processing chamber 100.

In the embodiment depicted in FIG. 1, the electrode 180 is coupled,through a matching circuit 188, to a first RF power source 184 and asecond RF power source 186. The sources 184, 186 are generally capableof producing an RF signal having a frequency from about 50 kHz to about3 GHz and a power of up to about 10,000 Watts. The matching network 188matches the impedance of the sources 184, 186 to the plasma impedance. Asingle feed couples energy from both sources 184, 186 to the electrode180. Alternatively, each source 184, 186 can be coupled to the electrode180 via a separate feed.

The electrostatic chuck 166 may also include at least one embeddedheater 176 controlled by a power supply 178. The electrostatic chuck 166may further comprise a plurality of gas passages (not shown), such asgrooves, that are formed in a substrate supporting surface of the chuckand fluidly coupled to a source of a heat transfer (or backside) gas. Inoperation, the backside gas (e.g., helium (He)) is provided atcontrolled pressure into the gas passages to enhance the heat transferbetween the electrostatic chuck 166 and the substrate 144.Conventionally, at least the substrate supporting surface 176 of theelectrostatic chuck is provided with a coating resistant to thechemistries and temperatures used during processing the substrates.

FIGS. 9-10 depict an exploded perspective view and a partial sectionalview of one embodiment of the outer liner 116. The outer liner 116 maybe fabricated and/or coated with a plasma or fluorine resistantmaterial. In one embodiment, the outer liner 116 is fabricated fromaluminum. In another embodiment, the outer liner 116 is fabricated fromor coated with Yttrium, Yttrium alloy or an oxide thereof. In yetanother embodiment, the outer liner 116 is fabricated from bulk Y₂O₃.The inner liner 118 may be fabricated from the same materials.

In the embodiment depicted in FIGS. 9-10, the outer liner 116 includesan upper liner 902 and a lower liner 904. An upper edge 908 of the lowerliner 904 is configured to mate with a lower edge 910 of the upper liner902, for example, in a rabbit joint.

The lower liner 904 is generally a hollow cylinder configured to fitsnugly against an interior surface 112 of the sidewalls 108. The lowerliner 904 includes a notch or port 906 that aligns with the exhaust port126 of the chamber body 102 to facilitate pump down and exhausting theinterior volume 106.

The upper liner 902 generally includes a body 914 having a flange 912extending from an upper portion thereof. The flange 912 is generallypolygonal in form, and in the embodiment depicted herein, the indices ofthe polygonal flange 912 are truncated at about a 45 degree angle.

The body 914 is generally cylindrical in form, having an inner wall 916and an outer all 934. A lip 918 extends inward from the inner wall 916and provides a supporting land for the showerhead assembly 130 onceinstalled in the chamber 100. An o-ring groove 920 is formed in the lip918 to provide a gas seal with the showerhead assembly 130.

An aperture 928 may be provided in the body 914 of the upper liner 902to allow visual inspection of the interior volume 106 through a window(not shown) formed in the chamber body 102. The portion of outer wall934 of the upper liner 902 surrounding the aperture 928 may be coveredby a removable window insert 924. The window insert 924 secured in adepression (not shown) in the upper liner 902 by a plurality offasteners 926 such that the insert 924 and outer wall 934 are flush.Thus, as the protect coating of the window insert 924 is worn fromcontact with the window/chamber body interface, the window insert 924may be replaced before the protective coating is broken through,exposing the base material of the outer liner 116.

A slot 938 is formed in the cylinder 914 to allow passage of thesubstrate into and out of the chamber 100. A recess 932 is formed in theouter wall 934 of the upper liner 902 surrounding the slot 938. Aremovable door insert 930 is disposed over the slot 938 to protect thesurface of the liner 902 from wear caused by contact with the slit valveport. The insert 930 has a slot 940 that aligns with the slot 938 formedin the upper liner 902 to facilitate substrate passage through the outerliner 116. The insert 930 is secured in the recess 932 by a plurality offasteners 936 such that the insert 930 and outer wall 934 are flush.Thus, as the protect coating of the insert 930 is worn from contact withthe slit valve port/chamber body interface, the insert 930 may bereplaced before the protective coating is broken through, exposing thebase material of the outer liner 116. The inserts 924, 930 are generallyfabricated from and/or coated with the same material as the liners.

FIG. 11 depicts on embodiment of inner liner 118 engaged with the coverring 146 that covers the outer upper surface of the substrate supportassembly 148. The inner liner 118 generally includes a larger diameterupper section 1140 and a smaller diameter lower section 1142. A slopedsection is defined on the outer diameter of the liner 188 to couple thelarger diameter upper section 1140 and the smaller diameter lowersection 1142.

A flange 1132 extends inward from the junction of the sections 1140,1142. The flange 1132 has a bottom surface 1134 that locates the innerliner 118 with the substrate support assembly 148. An o-ring groove 1136is formed in an upper surface of the flange 1132 to seal the inner liner118.

The cover ring 146 is disposed on the substrate support assembly 148 andis interleaved with an upper end 1128 of the inner liner 118. The coverring 146 generally has an annular body 1102 formed and/or coated with anplasma and/or chemistry resistant material. In one embodiment, the coverring 146 is fabricated from and/or coated with Yttrium or an oxidethereof. In one embodiment, the gas cover ring 146 is fabricated frombulk Yttrium to provide resistance to fluorinated chemistries. Inanother embodiment, the cover ring 146 is fabricated from quartz.

The body 1102 generally has a top surface 1104 and a bottom surface1126. A first ridge 1118, a second ridge 1122 and a third ridge 1120extending downward from the bottom surface 1126 of the body 1102. In theembodiment depicted in FIG. 11, the ridges 1118, 1122, 1120 areconcentric rings.

The first and second ridges 1118, 1122 are disposed on the inner portionof the cover ring 146, and define a slot therebetween that captures theupper end 1128 of the inner liner 118 therein. The first ridge 1118extends further from the body 1102 than the second ridge 1122. The thirdridge 1120 also extends further from the body 1102 than the second ridge1122. The third ridge 1120 extends into a slot 1180 formed in thesubstrate support assembly 148, thereby fixing the orientation betweenthe cover ring 146 and support assembly 148.

A tab 1116 extends radially inward from the body 1102 proximate thethird ridge 1120. The tab 1116 includes an upper surface 1150 that issubstantially coplanar with an upper surface 1152 of the electrostaticchuck 166. The perimeter of the substrate (not shown in FIG. 11) coversthe interface between the electrostatic chuck 166 and the upper surface1150 of the tab 1116 when the substrate is disposed on the substratesupport assembly 148.

An inner wall 1114 is disposed between the tab 1116 and the top surface1104 of the body 1102. The inner wall 1114 has a diameter greater thanan inside diameter of the tab 1116. Typically, the diameter of the innerwall 1114 is selected to provide adequate clearance with the substrate.

The top surface 1104 of the body 1102 generally includes an inner region1110 and an outer region 1108. The inner region 1110 is raised relativeto the outer region 1108. The inner region 1110 may be orientatedparallel to the outer region 1108 of the top surface 1104. In theembodiment depicted in FIG. 11, a sloped region 1112 defines thetransition between the inner and outer regions 1110, 1108 of the topsurface 1104.

FIG. 11 also includes details of one embodiment of the electrostaticchuck 166. The electrostatic chuck 166 includes a stepped outer diametersurface defined between the upper surface 1152 and a lower surface 1198of the chuck. The stepped outer diameter generally includes of an upperwall 1188, a middle wall 1192 and a lower wall 1196. The walls 1188,1192, 1196 are generally vertical, with the upper wall 1188 beingshorter than the middle wall 1192. The middle wall 1192 is shorter thanthe lower wall 1196. The upper wall 1188 begins at the upper surface1152 and extends downward to an upper ledge 1190. The upper ledge 1190couples the upper wall 1188 to the middle wall 1192. A lower ledge 1194couples the middle wall 1192 and the lower wall 1196. The lower wall1196 is coupled to the bottom surface 1198. The ledges 1190, 1194 aregenerally horizontal, with the lower ledge 1194 being larger than theupper ledge 1190. The stepped outer diameter created by the walls 1188,1192, 1196 and ledges 1190, 1192 create a contoured profile that mateswith and retains the cover ring 146 in a predetermined position on thesubstrate support assembly 148.

In operation, the processing chamber 100 may be utilized to etch a highaspect ratio feature in a substrate. In one embodiment, a method foretching a high aspect ratio trench in a silicon layer disposed on asubstrate may be performed in the chamber 100. The silicon layer iscovered with a patterned mask, as is conventionally practiced. Themethod begins by regulating the chamber pressure between about 0 toabout 300 milliTorr (mT). The substrate is biased with about 500 toabout 2800 Watts (W) of bias power. In one embodiment, the bias power isapplied at a frequency of about 2 MegaHertz (MHz).

A plasma, formed from the gases provided through the multiple gas flowzones of the showerhead assembly, is maintained by the application ofabout 500 to about 2800 W to the substrate support assembly. In oneembodiment, the power is applied at 60 MHz. A magnetic B-field isapplied across the chamber having between about 0 about 140 Gauss (G).The silicone layer is plasma etched through the openings in the mask toform a trench having an aspect ratio up to at least 80:1.

A mixture of process, direct injection and inert gases are provided tothe chamber for plasma etching. The mixture may include at least one ofHBr, NF₃, O₂, SiF₄, SiCl₄ and Ar. In one embodiment, the process gasesprovided to the mixing manifold include HBr and NF₃, while O₂, SiF₄ andSiCl₄ may optionally be provided. In an exemplary embodiment, betweenabout 50 to about 500 sccm of HBr, between about 10 to about 200 sccm ofNF₃, between about 0 to about 200 sccm of O₂, between about 0 to about200 sccm of SiF₄, between about 0 to about 200 sccm of SiCl₄, andbetween about 0 to about 200 sccm of Ar are provided to the mixingmanifold for a process suitable for etching a 300 mm substrate. Themixed gases are provided to the plenums at a flow ratio selectedcommensurate with the feature density, size and lateral location. SiCl₄may be used as a direct injection gas provided to the plenums of theshowerhead assembly bypassing the mixing manifold.

It has been demonstrated that the processing chamber described aboveetches high aspect ratio features chamber with good uniformity acrossthe surface of the substrate. Comparison data between etch siliconprocesses performed in convention processing chambers and the processingchamber described above illustrates an improvement of edge to centeraspect ratio uniformity. Conventional systems may have an edge to centeraspect ratio of about 1.35, while the processing chamber described abovehas an edge to center aspect ratio of about 1.04, making the inventivechamber suitable for fabrication of next generation devices.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A showerhead assembly, comprising: a gas distribution plate having anouter set of gas flow holes, an inner set of gas flow holes, and a setof optical metrology holes; an upper section coupled to the gasdistribution plate and having a first plenum fluidly coupled to theouter set of gas flow holes and a second plenum fluidly coupled to theinner set of gas flow holes, the plenums being fluidly isolated withinthe upper section; and a ceramic plug disposed through the upper sectionand having an optically transmissive region aligned with the opticalmetrology holes.
 2. The showerhead assembly of claim 1 furthercomprising: a window disposed through the upper section and aligned withthe plug.
 3. The showerhead assembly of claim 2, wherein the windowfurther comprises: a material transmissive to a signal utilized by anoptical monitoring system.
 4. The showerhead assembly of claim 2,wherein the window further comprises quartz.
 5. The showerhead assemblyof claim 2, wherein the upper section further comprises: a base having arecess formed therein, the gas distribution plate covering the recess,wherein the window is disposed in the recess.
 6. The showerhead assemblyof claim 1, wherein the gas distribution plate is fabricated from bulkYttria.
 7. The showerhead assembly of claim 1, wherein the opticallytransmissive region further comprises a plurality of high aspect ratioholes.
 8. The showerhead assembly of claim 1 further comprising:concentric rings of adhesive coupling the gas distribution plate to theupper section, wherein the concentric rings form radially isolatedconcentric plenums defined between gas distribution plate and the uppersection.
 9. The showerhead assembly of claim 8 further comprising: beadsof adhesive disposed between concentric rings of adhesive, wherein gasespresent between the gas distribution plate, the upper section and a pairof adhesive rings may flow around the beads.
 10. The showerhead assemblyof claim 1, wherein the upper section further comprises: a base having astepped recess; a first plate disposed in the recess; a second platedisposed in the recess between the first place and the base; and abarrier wall disposed between the first and second plates and separatingthe first and second plenums.
 11. The showerhead assembly of claim 10,wherein the upper section further comprises: a plurality of pins spacingthe first plate from the second plate.
 12. The showerhead assembly ofclaim 11, wherein the pins are press fit into the first and secondplates.
 13. The showerhead assembly of claim 11, wherein the first platecomprises a pluarity of gas passages, wherein each gas passage furthercomprises: an orifice hole disposed between a first bore hole and asecond bore hole, wherein bore holes have substantially greater diameterand depth relative to the orifice hole.
 14. A showerhead assembly,comprising: an upper section having a plurality of gas flow passagesseparating an upper plenum from a lower plenum; a gas distribution platecoupled to the upper section and having a plurality of gas flow holesfluidly coupled to the lower plenum; and an optically transmissivepassage defined though the upper section and the gas distribution plate.15. The showerhead assembly of claim 14, wherein the opticallytransmissive passage further comprises: a sealed window; and a memberdisposed between the window and the gas distribution plate; and aplurality of high aspect ratio holes formed in the member.
 16. Theshowerhead assembly of claim 14, wherein the high aspect ratio holeshave an aspect ratio (height to diameter) of at least about 10:1. 17.The showerhead assembly of claim 14, wherein the high aspect ratio holeshave a diameter of less than or comparable at least one of a DEBYElength and/or the electron mean free path.
 18. The showerhead assemblyof claim 14, wherein the high aspect ratio holes have a diameter lessthan about 1.5 mm.
 19. The showerhead assembly of claim 14, wherein thehigh aspect ratio holes define an open area of up to about 60 percentopen area.
 20. The showerhead assembly of claim 14, wherein the highaspect ratio holes have 37 holes.
 21. The showerhead assembly of claim14, wherein the member further comprises ceramic.
 22. The showerheadassembly of claim 14, wherein the upper section further comprises: abase having a stepped recess; a first plate disposed in the recess; asecond plate disposed in the recess between the first place and thebase; and a barrier wall disposed between the first and second platesand separating the first and second plenums.
 23. The showerhead assemblyof claim 22, wherein the upper section further comprises: a plurality ofpins spacing the first plate from the second plate.
 24. The showerheadassembly of claim 22, wherein the pins are press fit into the first andsecond plates.
 25. The showerhead assembly of claim 22, wherein thefirst plate comprises a pluarity of gas passages, wherein each gaspassage further comprises: an orifice hole disposed between a first borehole and a second bore hole, wherein bore holes have substantiallygreater diameter and depth relative to the orifice hole.
 26. Theshowerhead assembly of claim 14, wherein the gas distribution plate isfabricated from bulk Yttria.
 27. The showerhead assembly of claim 14,wherein the optically transmissive region further comprises a pluralityof high aspect ratio holes.
 28. The showerhead assembly of claim 14further comprising: concentric rings of adhesive coupling the gasdistribution plate to the upper section, wherein the concentric ringsform radially isolated concentric plenums defined between gasdistribution plate and the upper section.
 29. The showerhead assembly ofclaim 28 further comprising: beads of adhesive disposed betweenconcentric rings of adhesive, wherein gases present between the gasdistribution plate, the upper section and a pair of adhesive rings mayflow around the beads.
 30. A showerhead assembly, comprising: a basehaving a stepped recess; a first plate disposed in the recess; a secondplate disposed in the recess between the first place and the base; aceramic plug having a plurality a high aspect ratio holes formedtherethrough, the high aspect ratio holes have a diameter less thanabout 1.5 mm and an aspect ratio (height to diameter) of at least about10:1; a barrier wall disposed between the first and second plates andseparating a first and second plenums defined the first and secondplates; a gas distribution plate coupled to the first plate by aplurality of concentric adhesive lines and having a plurality of gasflow holes aligned between adhesive lines; and an optically transmissivepassage defined though the base, plates, and ceramic plug and the gasdistribution plate.